Enhancement of Static and Dynamic Performance of Composite Tapered Pretwisted Rotating Blade With Variable Stiffness

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Touraj Farsadi
Keyword(s):  
Performance Metrics ◽  
Dynamic Performance ◽  
Variable Stiffness ◽  
Coupling Factor ◽  
Element Analysis ◽  
Structural Part ◽  
Fiber Placement ◽  
Thin Walled ◽  
Fiber Path ◽  
Curvilinear Fibers

Abstract Composite pretwisted tapered rotating thin-walled beams (TWB) can be used as a load-carrying structural part of a composite helicopter, wind turbine, fan, and turbomachinery blades. In the present study, the variable stiffness concept with curvilinear fiber path is used to achieve improved structural statics and dynamics performance of uniform and asymmetric composite thin-walled rotating beams. A parametric study is performed to investigate the effect of different fiber paths on the structural performance metrics including frequency spacing, coupling factor, and critical buckling load. For this purpose, The Euler–Lagrange governing equations of the dynamic system are derived via Hamilton's principle. To solve the governing set of equations, the extended Galerkin’s method (EGM) is employed. To validate the TWB model with curvilinear fibers, commercial finite element analysis tools abaqus is used. The author believes that the results presented here are likely to provide valuable information to the engineers involved in the design of advanced turbomachinery rotating blades using a variable stiffness concept with curvilinear fiber placement.

Improvement of structural characteristics of composite thin-walled beams using variable stiffness concept via curvilinear fiber placement

2021 ◽  
pp. 095441002098824
Author(s):  
Touraj Farsadi ◽  
Mirac Onur Bozkurt ◽  
Demirkan Coker ◽  
Altan Kayran
Keyword(s):  
Performance Metrics ◽  
Structural Characteristics ◽  
Variable Stiffness ◽  
Structural Performance ◽  
Fe Method ◽  
Fiber Placement ◽  
Thin Walled ◽  
Fiber Path ◽  
Curvilinear Fibers ◽  
Straight Fiber

This study presents the use of variable stiffness concept via curvilinear fiber placement to achieve improved structural characteristics in composite thin-walled beams (TWBs). The TWB used in the study is constructed in circumferentially asymmetric stiffness (CAS) configuration. The variation of fiber angles along the span and the width of the TWB is included by defining two fiber path functions. A parametric study is performed to investigate the effects of different fiber paths on the structural performance metrics including frequency spacing, unit twist, and critical buckling load. For this purpose, a semi-analytical solution method is developed to conduct free vibration, deformation, and buckling analyses of the TWB with curvilinear fibers. The semi-analytical method is validated with several finite element (FE) analyses performed using ABAQUS. Elastic stress analyses of TWBs with selected fiber paths subjected to simplified distributed loading are also conducted using the FE method, and a ply failure criterion is applied to evaluate the strength of these TWBs. Overall results show that curvilinear fiber placement varied along the span leads to greater structural performance for a composite TWB than the straight fiber configuration.

Size-dependent behavior of laminates with curvilinear fibers made by automated fiber placement

2015 ◽  
Vol 22 (2) ◽  
pp. 157-163 ◽  
Author(s):  
Mahdi Arian Nik ◽  
Larry Lessard ◽  
Damiano Pasini
Keyword(s):  
Variable Stiffness ◽  
Buckling Load ◽  
Fiber Placement ◽  
Plate Size ◽  
Load Increase ◽  
Automated Fiber Placement ◽  
Fiber Path ◽  
Turning Radius ◽  
Curvilinear Fibers ◽  
Minimum Turning Radius

AbstractVariable stiffness laminates can be manufactured using curvilinear fiber paths. A curvilinear fiber path is generally defined based on the plate size and has a curvature that is dependent on the plate size. In practice, however, the fiber path must satisfy manufacturing constraints, such as the minimum turning radius imposed by the automated fiber placement machine, thereby limiting the possible amount of fiber steering. In this work, we studied the effect of the plate size on the structural properties of a plate manufactured with curvilinear fibers. We considered four plate sizes, which were designed by a constant curvature fiber path. We optimized the plates for both maximum buckling load and in-plane stiffness. The results showed that the in-plane stiffness of the plate was not controlled by the plate size, whereas the buckling load was highly affected by the curvature of the fiber path. Hence, the potential of a buckling load increase reduced for plate sizes smaller than the minimum turning radius. In addition, for a given maximum curvature of the fiber path, the influence of a complex layup on the buckling load was marginal.

scholarly journals Optimizing Variable-Axial Fiber-Reinforced Composite Laminates: The Direct Fiber Path Optimization Concept

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Lars Bittrich ◽  
Axel Spickenheuer ◽  
José Humberto S. Almeida ◽  
Sascha Müller ◽  
Lothar Kroll ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Variable Stiffness ◽  
Tensile Specimen ◽  
Path Optimization ◽  
Fiber Reinforced ◽  
Simulation And Optimization ◽  
Fiber Placement ◽  
Fiber Path ◽  
Curvilinear Fibers ◽  
Novel Concept

The concept of aligning reinforcing fibers in arbitrary directions offers a new perception of exploiting the anisotropic characteristic of the carbon fiber-reinforced polymer (CFRP) composites. Complementary to the design concept of multiaxial composites, a laminate reinforced with curvilinear fibers is called variable-axial (also known as variable stiffness and variable angle tow). The Tailored Fiber Placement (TFP) technology is well capable of manufacturing textile preforming with a variable-axial fiber design by using adapted embroidery machines. This work introduces a novel concept for simulation and optimization of curvilinear fiber-reinforced composites, where the novelty relies on the local optimization of both fiber angle and intrinsic thickness build-up concomitantly. This framework is called Direct Fiber Path Optimization (DFPO). Besides the description of DFPO, its capabilities are exemplified by optimizing a CFRP open-hole tensile specimen. Key results show a clear improvement compared to the current often used approach of applying principal stress trajectories for a variable-axial reinforcement pattern.

The effect of the percentage of steered plies on the bending-induced buckling performance of a variable stiffness composite cylinder

2015 ◽  
Vol 22 (2) ◽  
pp. 149-156 ◽  
Author(s):  
Mohammad Rouhi ◽  
Hossein Ghayoor ◽  
Suong V. Hoa ◽  
Mehdi Hojjati
Keyword(s):  
Performance Improvement ◽  
Design Procedure ◽  
Laminated Composite ◽  
Variable Stiffness ◽  
Design Parameters ◽  
Composite Cylinder ◽  
Element Analysis ◽  
Fiber Placement ◽  
Structural Improvement ◽  
Automated Fiber Placement

AbstractThe fiber steering capability of automated fiber placement machines offers the designers more room to fully exploit the directional properties of composite materials. Circumferential stiffness tailoring by fiber steering can considerably increase the bending-induced buckling performance of laminated composite cylinders. The potential structural improvement resulting from fiber steering depends on different design parameters such as the number of plies considered for fiber steering in a laminate. In this study, the buckling performance improvement of a variable stiffness (VS) composite cylinder is investigated for different percentages of plies considered for fiber steering in a multilayered composite laminate. A surrogate-based modeling along with a multi-step optimization is used in the design procedure of this study. The improvements in the buckling performance are shown and verified using finite element analysis in ABAQUS software. The mechanisms leading to buckling performance improvement of VS composites are also investigated and presented for different percentages of fiber-steered plies.

scholarly journals Multi-Objective Optimization of Variable-Stiffness Composites Fabricated by Tailored Fiber Placement Machine

2019 ◽  
Vol 2 (1) ◽  
pp. 14-18
Author(s):  
Shinya Honda
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Variable Stiffness ◽  
Optimization Method ◽  
Pareto Optimum ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Fiber Placement ◽  
Curvilinear Fibers ◽  
Placement Machine

A multi-objective optimization method for the laminated composite fabricated by a tailored fiber placement machine that is an application of embroidering machine is presented. The mechanical properties of composite with curvilinear fibers including stiffness, volume fraction, and density are variable depending on curvatures of fibers. The present study first measures the relation between curvatures and mechanical properties. The measured results indicate that the stiffness of composite decreases linearly as the curvature increases. Then, the obtained relation is applied to the multi-objective optimization where the maximum principal strain and magnitude of curvature are employed as objective functions. Obtained Pareto optimum solutions are widely distributed ranging from the solutions with curvilinear fibers to those with straight fibers, and the curvilinear fiber has still advantages over straight fiber even its weakened stiffness.

Macroscopic characterization of fiber micro-buckling and its influence on composites tensile performance

2016 ◽  
Vol 36 (3) ◽  
pp. 196-205 ◽  
Author(s):  
Cong Zhao ◽  
Bendong Wang ◽  
Jun Xiao
Keyword(s):  
Tensile Properties ◽  
Mechanical Performance ◽  
Tensile Modulus ◽  
Geodesic Curvature ◽  
Curvature Radius ◽  
Element Analysis ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Fiber Path ◽  
Microscopic Distribution

As one of the most common defects induced by Automated Fiber Placement, in-plane fiber micro-buckling is characterized by a macroscopic value and its influence on composites tensile properties are studied in this article. The mathematical relationship between fiber microscopic distribution and geodesic curvature of non-geodesic fiber path is derived. Influences of in-plane fiber micro-buckling on tensile properties are analyzed by off-axis tensile theory and finite element analysis, and verified by experiments. Actual fiber microscopic distribution of in-plane fiber micro-buckling shows that it is reasonable to evaluate the scale of fiber micro-buckling by the geodesic curvature radius of curved fiber trajectory. Longitudinal tensile properties of lamina are dramatically influenced by in-plane fiber micro-buckling, while the influences of in-plane fiber micro-buckling on transversal tensile properties can be ignored. When A/ L reaches 0.023, the longitudinal tensile modulus and strength of lamina decreased by 25.5% and 57.7%, respectively, compared with the lamina without any defects. Based on the conclusions made in this article, the scale of in-plane fiber micro-buckling can be predicted without metallographic observation. And the increase of structural efficiency and the loss of mechanical performance in consequence of non-geodesic fiber path could be evaluated for the optimization of fiber trajectory.

scholarly journals Coulomb-actuated microbeams revisited: experimental and numerical modal decomposition of the saddle-node bifurcation

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Anton Melnikov ◽  
Hermann A. G. Schenk ◽  
Jorge M. Monsalve ◽  
Franziska Wall ◽  
Michael Stolz ◽  
...  
Keyword(s):  
Finite Element ◽  
Microelectromechanical Systems ◽  
Dynamic Range ◽  
Dynamic Performance ◽  
Major Step ◽  
Element Analysis ◽  
Electrostatic Actuators ◽  
Voltage Range ◽  
Drive Voltage ◽  
Depth Analysis

AbstractElectrostatic micromechanical actuators have numerous applications in science and technology. In many applications, they are operated in a narrow frequency range close to resonance and at a drive voltage of low variation. Recently, new applications, such as microelectromechanical systems (MEMS) microspeakers (µSpeakers), have emerged that require operation over a wide frequency and dynamic range. Simulating the dynamic performance under such circumstances is still highly cumbersome. State-of-the-art finite element analysis struggles with pull-in instability and does not deliver the necessary information about unstable equilibrium states accordingly. Convincing lumped-parameter models amenable to direct physical interpretation are missing. This inhibits the indispensable in-depth analysis of the dynamic stability of such systems. In this paper, we take a major step towards mending the situation. By combining the finite element method (FEM) with an arc-length solver, we obtain the full bifurcation diagram for electrostatic actuators based on prismatic Euler-Bernoulli beams. A subsequent modal analysis then shows that within very narrow error margins, it is exclusively the lowest Euler-Bernoulli eigenmode that dominates the beam physics over the entire relevant drive voltage range. An experiment directly recording the deflection profile of a MEMS microbeam is performed and confirms the numerical findings with astonishing precision. This enables modeling the system using a single spatial degree of freedom.

scholarly journals Experimental Investigation on the Influence of Fiber Path Curvature on the Mechanical Properties of Composites

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2602
Author(s):  
Huaqiao Wang ◽  
Jihong Chen ◽  
Zhichao Fan ◽  
Jun Xiao ◽  
Xianfeng Wang
Keyword(s):  
Tensile Strength ◽  
Path Planning ◽  
Composite Laminates ◽  
Bending Strength ◽  
High Strength ◽  
Bending Test ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Fiber Path ◽  
Path Curvature

Automated fiber placement (AFP) has been widely used as an advanced manufacturing technology for large and complex composite parts and the trajectory planning of the laying path is the primary task of AFP technology. Proposed in this paper is an experimental study on the effect of several different path planning placements on the mechanical behavior of laminated materials. The prepreg selected for the experiment was high-strength toughened epoxy resin T300 carbon fiber prepreg UH3033-150. The composite laminates with variable angles were prepared by an eight-tow seven-axis linkage laying machine. After the curing process, the composite laminates were conducted by tensile and bending test separately. The test results show that there exists an optimal planning path among these for which the tensile strength of the laminated specimens decreases slightly by only 3.889%, while the bending strength increases greatly by 16.68%. It can be found that for the specific planning path placement, the bending strength of the composite laminates is significantly improved regardless of the little difference in tensile strength, which shows the importance of path planning and this may be used as a guideline for future AFP process.

Finite Element Analysis and Optimization of Long-Span Gantry NC Machining Center Structure

2011 ◽  
Vol 346 ◽  
pp. 379-384
Author(s):  
Shu Bo Xu ◽  
Yang Xi ◽  
Cai Nian Jing ◽  
Ke Ke Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Method ◽  
Dynamic Performance ◽  
Plate Thickness ◽  
Element Model ◽  
Wall Structure ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
Dynamic Performance Analysis

The use of finite element theory and modal analysis theory, the structure of the machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important. Selected for three-dimensional CAD modeling software-UG NX4.0 and finite element analysis software-ANSYS to set up the structure of the beam finite element model, and then post on the overall structure of the static and dynamic characteristic analysis, on the basis of optimized static and dynamic performance is more superior double wall structure of the beam. And by changing the wall thickness and the thickness of the inner wall, as well as the reinforcement plate thickness overall sensitivity analysis shows that changes in these three parameters on the dynamic characteristics of post impact. Application of topology optimization methods, determine the optimal structure of the beam ultimately.

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